Formation Of Clusters Research Articles

An innovative and efficient approach for searching and selecting web services operations

The marketing of web services on the internet continues to increase, resulting in an increasing number of web services and, therefore, operations offering equivalent functionalities. As a consequence, finding an appropriate web service (operation) for a particular task has become a difficult challenge, taking a lot of time and leading to an insufficient selection of relevant services. This work aims to propose a new approach facilitating the search and localization of relevant web services (operations) in an acceptable time while ensuring the totality of the response. This approach is divided into three crucial phases. The first step involves collecting web services from various universal description, discovery, and integration (UDDI) registries and different domains and forming specialized sub-registries. The second phase involves the extraction of operations from various services, followed by a similarity study whose goal is the formation of clusters of similar operations. The third phase processes user requests by identifying the desired features. A list of operations is then provided to the client, including the non-functional properties, from which they select the one that best meets their needs and begin to invoke it.

Investigation of the Impact of Thionine Functionalization on Magnetoelastic Sensor Performance.

This study investigates the functionalization of gold-coated magnetoelastic sensors with thionine molecules, focusing on resonance frequency shifts. The functionalization process was characterized by using Raman spectroscopy and analyzed via scanning electron microscopy and atomic force microscopy, revealing the progressive formation of molecular clusters over time. Our results demonstrate that longer functionalization time leads to saturation of surface coverage and cluster formation, impacting the sensor's resonance frequency shifts. Such modifications offer insights into the adsorption process of these molecules on the sensor's gold surface, as well as its performance.

Coupling Cu2O clusters and imine-linked COFs on microfiltration membranes for fast and robust water sterilization

As bacterial contamination crises escalate, the development of advanced membranes possessing both high flux and antibacterial properties is of paramount significance for enhancing water sterilization efficiency. Herein, an ultrathin layer of TbPa (an imine-linked covalent organic framework) and nanosized Cu2O clusters, sequentially deposited onto polyethersulfone membranes, demonstrate exceptional water flux performance, reaching a permeance level of 16000 LHM bar−1. The deposited TbPa, generating uniformly distributed reduction sites under illumination, facilitates the uniform formation of Cu2O clusters. Furthermore, these anchored Cu2O clusters significantly optimize electron transport within the ultra-thin layer of TbPa, thereby enhancing the performance of the membrane in generating reactive oxygen species (ROS). Consequently, this membrane achieves a flux recovery rate exceeding 98.6% for flux losses caused by bacterial fouling and maintains consistent performance over 10 cycles. This work presents an effective strategy for accessing bactericidal membranes and provides insights into efficient and mild water sterilization.

Wound Healing in Butterfly Pupal Wing Tissues: Real-Time In Vivo Imaging of Long-Range Cell Migration, Cluster Formation, and Calcium Oscillations

Insects can repair wounds and regenerate body parts in response to physical damage. Wound healing in butterfly pupal wing tissues is developmentally interesting because ectopic color patterns develop during healing, suggesting that normal and damage-induced color patterns may use similar mechanisms. Here we physiologically investigated wound healing and ectopic color pattern formation in butterfly pupal wing tissues using the blue pansy butterfly Junonia orithya. In response to physical puncture damage, various ectopic color patterns are formed around the damage site. After the wounding operation, we observed hemocytes migrating over long distances along the wing veins (lacunae) toward the damage site, where hemocytes and epidermal cells formed cellular clusters. Calcium oscillations were observed in cells at and near the damage site. Calcium oscillations were transiently affected by ruthenium red, an inhibitor of calcium transporters and channels, and ruthenium red caused various abnormalities in the scales of adult wings. These results suggest that cell migration, cluster formation, and calcium oscillations play important roles in wound healing and scale development at and near the damage site. Ectopic color patterns may develop in response to local calcium oscillations as a consequence of the evolutionary co-option of the healing process for normal development.

Emission Tuning of Nonconventional Luminescent Materials via Cluster Engineering.

Nonconventional Luminescent Materials (NLMs) with distinctive optical properties are garnering significant attention. A key challenge in their practical application lies in precisely controlling their emission behavior, particularly achieving excitation wavelength-independent emission, which is paramount for accurate chemical sensing. In this study, NLMs (Y1, Y2, Y3, and Y4) are synthesized via a click reaction, and it is found that excitation wavelength-dependent emission correlates with molecular cluster formation. Rigid NLMs (Y1, Y2) exhibit excitation-independent emission in dilute solutions with nanoscale clusters but become excitation-dependent at higher concentrations due to larger cluster formation. Flexible NLMs (Y3 and Y4) always show excitation-dependent emission, indicating a tendency for larger cluster formation. While these NLMs exhibit high photoluminescence quantum yields (PLQYs) in dilute solutions (0.1 mgmL-1) up to 38.0%, they suffer from significant aggregation-caused quenching (ACQ) in the solid state (as low as 0.5%). These findings provide insights into NLM luminescence mechanisms and offer a new approach for tuning their optical properties. With excellent optical properties, facile synthesis, and biocompatibility, these NLMs hold promise for bioimaging and other applications.

Far-Ultraviolet Plexciton Formation in Water-Covered Indium Clusters.

In this work, we study the plexciton in the far-ultraviolet region formed between indium nanoclusters and water molecules. The indium clusters are fabricated on graphene under ultrahigh vacuum conditions and show a strong localized surface plasmon polariton (LSP) absorption band at 6-7 eV. Adsorption of water molecules onto the clusters at 115 K induces a band splitting larger than 1 eV, indicating a strong coupling between the LSP and water 4a1 ← 1b1 transition. The spectral evolution as a function of the water coverage is revealed, enabling the determination of the decay length of the plexciton collective effect to be ∼8 nm.

Chemical enrichment by collapsars as the origin of the unusually high [Ba/Fe] in a massive star cluster of the dwarf galaxy NGC 1569

Abstract The super star cluster NGC1569-B has recently been observed to have an extremely high [Ba/Fe]. We consider that the observed high [Ba/Fe] (∼1.3) is due to the chemical enrichment of giant molecular clouds by either collapsars, neutron star mergers, or magneto-rotational supernovae, and thereby investigate which of the three polluters can best reproduce the observed [Ba/Fe]. Since it is found that collapsars can best reproduce such an extremely high Ba abundance, we numerically investigate the star cluster formation in NGC1569 using chemodynamical simulations of merging dwarf galaxies with chemical enrichment by collapsars. The principal results are as follows. First, a cluster of the same scale as NGC1569-B was found to match both the observed [Ba/Fe] and [Fe/H] values, the best cluster having [Ba/Fe]=1.3 ± 0.2 and [Fe/H] =−0.7 ± 0.2. This simulation used a core-collapse supernova per collapsar rate of 70, a standard initial mass function and an initial metallicity of [Fe/H]=-1.5. Second, a prediction of the Eu abundance of NGC1569-B is made: [Eu/Fe]=1.9 ± 0.2. These results are shown to be invariant under a change in the orbit parameters used for the merger. The need for a merger to promote the star formation that leads to the synthesis of the Ba and the star cluster formation is confirmed. Collapsars can not only better explain [Ba/Fe] but also be consistent with the observed star formation rate and stellar mass of the dwarf galaxy.

Assessment and Examination of Emergency Management Capabilities in Chinese Rural Areas from a Machine Learning Perspective

The Chinese government’s rural rejuvenation program depends on improving the national Rural Emergency Management Capability (REMC). To increase the resilience of Chinese rural areas against external dangers, REMC and its driving elements must be effectively categorized and evaluated. This study examines the variations in REMC levels and driving factors across different cities and regions, revealing the spatial distribution patterns and underlying mechanisms. To improve REMC in Chinese rural areas, this research employs the Projection Pursuit Method to assess REMC in 280 cities from 2006 to 2020. Additionally, we identify 22 driving factors and use the Random Forest algorithm from machine learning to analyze their impact on REMC. The analysis is conducted at both national and city levels to compare the influence of various driving factors in different regions. The findings show that China’s REMC levels have improved over time, driven by economic growth and the formation of urban clusters. Notably, some underdeveloped regions demonstrate higher REMC levels than more developed areas. The four most significant driving factors identified are rural road density, rural Internet penetration, per capita investment in fixed assets, and the density of township health centers. At the city level, rural Internet penetration and the e-commerce turnover of agricultural products have particularly strong driving effects. Moreover, the importance of driving factors varies across regions due to local conditions. This study offers valuable insights for the Chinese government to enhance REMC through region-specific strategies tailored to local circumstances.

Improving energy efficiency in wireless sensor networks (WSNs) using two-level fuzzy clustering and Artificial Bee Colony (ABC) optimization

ABSTRACT Improving network lifetime and energy efficiency in wireless sensor networks (WSNs) is a challenging but crucial issue. The ability to transport data over the network via a better route is a technology because of limitations on network lifetime and energy consumption. This paper presents a two-level fuzzy approach for optimising cluster formation and data routing in wireless networks. The approach focuses on determining cluster head nodes based on their unique properties, ensuring efficient cluster formation. The second level uses social traits to communicate among cluster nodes, calculating the cluster radius for better communication and data routing. The optimisation process also involves identifying optimal cluster head nodes and their corresponding radius for each cluster. Furthermore, we improved data routing by using the artificial bee colony technique, which included carefully selecting the best data transmission channels between the base station and the cluster head nodes. Thus, simulation results demonstrate that our technique outperforms other similar approaches in terms of energy usage, latency, packet transmissions, and average network lifespan. We tested the network performance from two perspectives: scalability and energy efficiency, in two stages. The experiments’ results demonstrated the superiority of the suggested approach over the methods that were compared.

Luminescence Characterization of the Green Synthesized Terbium Doped Titanium Oxide

Purpose: The purpose of this work is to prepare Titanium Oxide (TiO₂) with eco-friendly synthesis and also to study on structural, morphological, photoluminescence properties on Tb doped TiO₂. Methodology: Titanium Oxide was prepared by orange fruit aqueous extract as a reducing agent with addition of terbium as its dopant. Characterization of the synthesized TiO₂ was done by XRD proving that the TiO₂ was in the structural form of rutile as evidenced by the sharp peaks. The relationship between the concentration of Tb dopant and the grain size of the film layer was studied. SEM Morphological analysis indicated the formation of particle cluster at 1100°C. EDX spectroscopy was employed to determine the position of elements of the samples while FTIR spectroscopy was in agreement with carbonyl and hydroxyl groups being absent in the prepared samples. Optical characteristics of the samples were evaluated by photoluminescence measurements under the excitation of 400 nm wavelength. Findings: The results obtained in the present study pointed out how the terbium doping affected the structural and optical characterization of the TiO₂. An increase in the Tb concentration led to an increase in the grain size of the synthesized spherical film. Photoluminescence spectroscopy results showed two separate green and red emissions and was measured to have the highest intensity at 4% terbium concentration. From these results we can see the prospect of using Tb-doped TiO₂ in applications that require certain changes in the optical parameter. Contribution to Theory, Policy, and Practice: This work contributes to the body of knowledge on green synthesis methods for nanostructures and the effect of RE doping in improving the properties of a material. The results provide insight for green synthesis of photo luminescent materials, optoelectronic devices, and monitoring instruments, identifying ways to pursue environmentally friendly material design.

Which dimensions of regional diversity facilitate media cluster formation?

ABSTRACT This research investigates the relationship between regional diversity and media industry agglomeration by exploring multiple aspects of regional diversity, including cultural, economic, and demographic diversity, and their varying impacts on media industry agglomeration in South Korea. The findings of this study show that regions with great cultural and economic diversity attract the media industry. Exposure to diverse cultures and various economic activities enhances the region’s capacity to embrace unconventional thinking and innovative ideas, attracting creative talents who are vital to the media industry and promoting a conducive environment for creative activities within the media industry. However, this research also found that not all forms of regional diversity act as magnets for the media industry. Highlighting the multifaceted aspects of regional diversity, this study provides empirical evidence that, rather than a demographically diverse population, a demographically concentrated population of young labor attracts media industry agglomeration, facilitating the formation of media industry clusters.

Stabilizing Single-Atom Catalysts on Metastable Phases of Transition Metal Dichalcogenides.

Single-atom catalysts have attracted a significant amount of attention due to their exceptional atomic utilization and high efficiency in a range of catalytic reactions. However, these systems often face thermodynamic instability, leading to agglomeration under the operational conditions. In this study, we investigate the interactions of 12 types of catalytic atoms (Fe, Co, Ni, Cu, Ru, Rh, Pd, Ag, Ir, Pt, Au, and Bi) on three crystalline phases (1T, 1T', and 2H) of six transition metal dichalcogenide layers (MoS2, MoSe2, MoTe2, WS2, WSe2, and WTe2) using first-principles calculations. We ultimately identify 82 stable single-atom systems that thermodynamically prevent the formation of metal clusters on these substrates. Notably, our findings reveal that the metastable 1T and 1T' phases significantly enhance the binding strength with single atoms and promote their thermodynamic stability. This research offers valuable insights into the design of stable single-atom systems and paves the way for the discovery of innovative catalysts.

Klasterisasi Daerah Rawan Bencana Alam Menggunakan Algoritma K-Means

East Java is a province with high vulnerability to disasters, such as floods, landslides, earthquakes, and strong winds, which have an impact on material losses, casualties, and deterioration of socio-economic conditions, especially in rural areas. The lack of mitigation strategies and resource allocation worsens disaster management. This study aims to classify disaster data using the K-Means algorithm to overcome the limitations of descriptive analysis conducted by BPBD East Java. The data used includes 1125 disaster events with variable disaster frequency, total damage, and the number of casualties per sub-district in East Java districts and cities during 2021-2022, obtained from the official website of the East Java BPBD. The K-Means algorithm was chosen because of its efficiency in managing big data and its flexibility in cluster formation. The results of the study show that in 2021, the region in East Java is divided into three clusters based on the level of disaster risk: Cluster 1 (low risk) with 192 sub-districts, Cluster 2 (medium risk) with 35 sub-districts, and Cluster 3 (high risk) with 10 sub-districts. In 2022, significant changes were seen in Cluster 1, which includes 462 sub-districts, Cluster 2 with 20 sub-districts, and Cluster 3 with 11 sub-districts. The results of this study are expected to support the government's decision-making priorities, especially in disaster management and resource allocation based on risk levels

Nonthermal Plasma‐Catalytic Dry Reforming of Methane in Parallel‐Plate Dielectric Barrier Discharge Reactor Using Mg‐Modified Ni Catalysts

The conversion of greenhouse gases, particularly CO2 and CH4, into syngas via dry reforming of methane (DRM) has effectively mitigated global warming and climate change issues. The research objectives are to enhance the DRM efficiency and reduce coke formation using Ni catalysts supported on Mg‐modified Al2O3 in parallel plate dielectric barrier discharge. Raising the Ni calcination temperature from (Ni/Mg–Al2O3‐500) to 700 °C (Ni/Mg–Al2O3‐700) enhances NiO reduction temperatures, thus diminishing their reducibility. This indicates that Ni/Mg–Al2O3‐700 exhibits stronger NiO–Al2O3 interaction, resulting in increased metal dispersion and decreased crystallite and particle sizes. As the Ni calcination temperature increases from 700 to 800 °C (Ni/Mg–Al2O3‐800) the intensity of the Ni0.8Mg0.11Al2O4 spinel structure is enhanced. The increased Ni calcination temperature enhances the metal‐support sintering processes and promotes the metal nanoparticle cluster formation, leading to increased particle and crystallite sizes, alongside decreased dispersion of Ni and Mg particles on the catalyst surface. The Ni/Mg–Al2O3‐700 exhibits lowest NiO reducibility, strongest NiO–Al2O3 interaction, highest metal dispersion, highest specific surface area, smallest particle, and crystallite sizes. Consequently, it attains the highest CH4 and CO2 conversions, H2 and CO selectivities, and energy efficiency, as well as the lowest coking rate, carbon deposition, carbon loss, and specific energy consumption.

Low-mass runaways from the Orion Nebula Cluster - kinematic age constraints on star cluster formation

Low-mass runaways from the Orion Nebula Cluster - kinematic age constraints on star cluster formation

Clustering of obesogenic behaviours amongst 140052 South American adolescents: a harmonized meta-analysis of national health surveys.

Physical activity, sedentary behaviour, and diet synergically coexist (in different ways) within adolescents' lifestyles. Thus, understanding obesogenic behaviour patterns within populations is critical to promoting adolescents' health. This study investigates clustering patterns of adolescents' obesogenic behaviours across South American countries. The present work is a harmonized analysis of 10 national representative cross-sectional health surveys investigating adolescents' risk and protective factors for non-communicable diseases. The surveys used questionnaires, and three obesogenic behaviours were analyzed for cluster formation (physical activity, sitting time, and diet). Sociodemographic variables were sex, age, and food insecurity. The Two-step cluster, the Rao-Scott chi-square test, and a meta-analysis were performed for data analysis. Three to four cluster solutions were identified in each country, and most clusters are unhealthy. The All-day sitters-very poor diet cluster was observed in Paraguay, Peru, Suriname, Chile, Guyana, Argentina, Brazil, Colombia, and Ecuador, with a pooled prevalence of 17.8% (95% CI:15.0; 20.7) amongst South American countries, with the highest prevalence observed in Argentina [26.8% (95% CI: 26.7; 26.9)]. Girls were more likely to belong to the unhealthiest clusters. The lifestyle behaviours of South American adolescents coexist negatively, and there is a severe obesogenic risk for this population. The synergy between physical inactivity and poor/very poor diet was clustered together in all countries, and our analysis did not reveal any natural healthy clusters. Furthermore, girls are at a disadvantage, given that they are the majority in clusters with unhealthy profiles in South America.

Clustering of buoyant tracer in quasi-geostrophic coherent structures

We have investigated the dynamics of floating tracer in an idealised turbulent quasi-geostrophic ocean by advecting Lagrangian particles in a high-resolution velocity field enhanced by the potential flow associated with vortex stretching. At first order in the Rossby number expansion, this component of the ageostrophic circulation can be derived through a diagnostic equation in terms of the geostrophic velocities. Borrowing methods from the theory of Lagrangian coherent structures, we identify coherent material loops around strong vortex cores using the Lagrangian averaged vorticity deviation (LAVD). Building on studies of clustering in kinematic, stochastic velocity fields, we utilise methods from statistical topography to show that the coherent vortices dominate the distribution of extreme values of the concentration field. We find that the presence of clusters and voids in a coherent vortex depends on more than just the sense of rotation, but also on the full evolution of the vorticity over its lifecycle. We identify the mechanism behind the cluster formation that respects the symmetries of the quasi-geostrophic equations but can be expected to hold robustly in more complicated regimes, due to the simple physical description. The association of cluster formation with vortex stretching implies that LAVD is a particularly relevant metric for floating tracer dynamics. The detection of intense clustering also has implications for reaction rates between ocean-borne flotsam, meaning that our results are relevant to understanding the general risk of floating microplastics and marine biological populations.

Ultrastructural Study and Immunohistochemical Characteristics of Mesencephalic Tegmentum in Juvenile Chum Salmon (Oncorhynchus keta) Brain After Acute Traumatic Injury.

The ultrastructural organization of the nuclei of the tegmental region in juvenile chum salmon (Oncorhynchus keta) was examined using transmission electron microscopy (TEM). The dorsal tegmental nuclei (DTN), the nucleus of fasciculus longitudinalis medialis (NFLM), and the nucleus of the oculomotor nerve (NIII) were studied. The ultrastructural examination provided detailed ultrastructural characteristics of neurons forming the tegmental nuclei and showed neuro-glial relationships in them. Neurons of three size types with a high metabolic rate, characterized by the presence of numerous mitochondria, polyribosomes, Golgi apparatus, and cytoplasmic inclusions (vacuoles, lipid droplets, and dense bodies), were distinguished. It was found that large interneurons of the NFLM formed contacts with protoplasmic astrocytes. Excitatory synaptic structures were identified in the tegmentum and their detailed characteristic are provided for the first time. Microglia-like cells were found in the NIII. The ultrastructural characteristics of neurogenic zones of the tegmentum of juvenile chum salmon were also determined for the first time. In the neurogenic zones of the tegmentum, adult-type neural stem progenitor cells (aNSPCs) corresponding to cells of types III and IVa Danio rerio. In the neurogenic zones of the tegmentum, neuroepithelial-like cells (NECs) corresponding to cells previously described from the zebrafish cerebellum were found and characterized. In the tegmentum of juvenile chum salmon, patterns of paracrine neurosecretion were observed and their ultrastructural characteristics were recorded. Patterns of apoptosis in large neurons of the tegmentum were examined by TEM. Using immunohistochemical (IHC) labeling of the brain lipid-binding protein (BLBP) and aromatase B (AroB), patterns of their expression in the tegmentum of intact animals and in the post-traumatic period after acute injury to the medulla oblongata were characterized. The response to brainstem injury in chum salmon was found to activate multiple signaling pathways, which significantly increases the BLBP and AroB expression in various regions of the tegmentum and valvula cerebelli. However, post-traumatic patterns of BLBP and AroB localizations are not the same. In addition to a general increase in BLBP expression in the tegmental parenchyma, BLBP overexpression was observed in the rostro-lateral tegmental neurogenic zone (RLTNZ), while AroB expression in the RLTNZ was completely absent. Another difference was the peripheral overexpression of AroB and the formation of dense reactive clusters in the ventro-medial zone of the tegmentum. Thus, in the post-traumatic period, various pathways were activated whose components were putative candidates for inducers of the "astrocyte-like" response in the juvenile chum salmon brain that are similar to those present in the mammalian brain. In this case, BLBP acted as a factor enhancing the differentiation of both radial glia and neurons. Estradiol from AroB+ astrocytes exerted paracrine neuroprotective effects through the potential inhibition of inflammatory processes. These results indicate a new role for neuronal aromatization as a mechanism preventing the development of neuroinflammation. Moreover, our findings support the hypothesis that BLBP is a factor enhancing neuronal and glial differentiation in the post-traumatic period in the chum salmon brain.

GTD‐CER: Game‐Theoretic Dynamic Clustering for Enhanced Efficiency and Reliability in Wireless Sensor Networks

ABSTRACTEfficient cluster formation is a significant issue in wireless sensor networks (WSNs) for optimizing energy consumption, enhancing data reliability, and prolonging network lifetime. This paper proposes a dynamic cluster formation scheme modeled as a noncooperative game, where each sensor node acts as a player making strategic decisions on whether to become a cluster head (CH) or remain a member node (MN). In this role selection decision‐making phase, nodes evaluate their potential utility function, which incorporates energy consumption, data reliability, and data forwarding efficiency. Nodes dynamically switch roles based on their utility to achieve an optimal network configuration. Simulations conducted using the NS‐3 network simulator demonstrate that the proposed game theory‐based clustering scheme significantly improves network performance. We analyze key measures like energy consumption, packet delivery ratio (PDR), and data forwarding, and the results shows that the proposed scheme reduces energy consumption by 25%, improves PDR by 15%, and extends the network lifetime by 20%, compared to traditional methods. The dynamic role‐switching mechanism prolongs network lifetime by preventing the rapid depletion of node energy, ensuring stable and efficient network operations. It significantly enhances network performance, stability, and longevity.

Variation of the low-mass end of the stellar initial mass function with redshift and metallicity

Abstract We report the stellar mass functions obtained from 20 radiation hydrodynamical simulations of star cluster formation in 500 M⊙ molecular clouds with metallicities of 3, 1, 1/10 and 1/100 of the solar value, with the clouds subjected to levels of the cosmic microwave background radiation that are appropriate for star formation at redshifts z = 0, 3, 5, 7, and 10. The calculations include a thermochemical model of the diffuse interstellar medium and treat dust and gas temperatures separately. We find that the stellar mass distributions obtained become increasingly bottom light as the redshift and/or metallicity are increased. Mass functions that are similar to a typical Galactic initial mass function are obtained for present-day star formation (z = 0) independent of metallicity, and also for the lowest-metallicity (1/100 solar) at all redshifts up to z = 10, but for higher metallicities there is a larger deficit of brown dwarfs and low-mass stars as the metallicity and redshift are increased. These effects are a result of metal-rich gas being unable to cool to as lower temperatures at higher redshift due to the warmer cosmic microwave background radiation. Based on the numerical results we provide a parameterisation that may be used to vary the stellar initial mass function with redshift and metallicity; this could be used in simulations of galaxy formation. For example, a bottom-light mass function reduces the mass-to-light ratio compared to a typical Galactic stellar initial mass function, which may reduce the estimated masses of high-redshift galaxies.